vhost-user: add a new message to disable/enable a specific virt queue.

Add a new message, VHOST_USER_SET_VRING_ENABLE, to enable or disable
a specific virt queue, which is similar to attach/detach queue for
tap device.

virtio driver on guest doesn't have to use max virt queue pair, it
could enable any number of virt queue ranging from 1 to max virt
queue pair.

Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Jason Wang <jasowang@redhat.com>
Tested-by: Marcel Apfelbaum <marcel@redhat.com>

2 files changed, 26 insertions, 0 deletions

diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index ad82b5cce6..2bce89129d 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -422,6 +422,19 @@ VHostNetState *get_vhost_net(NetClientState *nc)
 
     return vhost_net;
 }
+
+int vhost_set_vring_enable(NetClientState *nc, int enable)
+{
+    VHostNetState *net = get_vhost_net(nc);
+    const VhostOps *vhost_ops = net->dev.vhost_ops;
+
+    if (vhost_ops->vhost_backend_set_vring_enable) {
+        return vhost_ops->vhost_backend_set_vring_enable(&net->dev, enable);
+    }
+
+    return 0;
+}
+
 #else
 uint64_t vhost_net_get_max_queues(VHostNetState *net)
 {
@@ -472,4 +485,9 @@ VHostNetState *get_vhost_net(NetClientState *nc)
 {
     return 0;
 }
+
+int vhost_set_vring_enable(NetClientState *nc, int enable)
+{
+    return 0;
+}
 #endif
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 2775e6a03e..d388c5571d 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -406,6 +406,10 @@ static int peer_attach(VirtIONet *n, int index)
         return 0;
     }
 
+    if (nc->peer->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER) {
+        vhost_set_vring_enable(nc->peer, 1);
+    }
+
     if (nc->peer->info->type != NET_CLIENT_OPTIONS_KIND_TAP) {
         return 0;
     }
@@ -421,6 +425,10 @@ static int peer_detach(VirtIONet *n, int index)
         return 0;
     }
 
+    if (nc->peer->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER) {
+        vhost_set_vring_enable(nc->peer, 0);
+    }
+
     if (nc->peer->info->type !=  NET_CLIENT_OPTIONS_KIND_TAP) {
         return 0;
     }